The entire disclosure of Japanese Patent Application No. 2001-347056 filed on Nov. 13, 2001 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to a multistage pressure condenser which has a plurality of chambers under different pressures, and which is designed to merge and pressure-feed condensates accumulated in the plurality of chambers.
2. Description of the Related Art
With steam turbine equipment, steam which has finished its work is introduced from a turbine exhaust hood into a condenser, where it is condensed to form condensate. The condensate formed by condensation in the condenser is heated via a feed water heater, and then supplied to a boiler to be formed into steam for use as a drive source for a steam turbine.
When the condensate formed by condensation in the condenser is fed to the feed water heater, the higher the temperature of the condensate, the more advantage is obtained in the aspect of plant efficiency. Thus, a multistage pressure condenser comprising a plurality of chambers at different pressures has so far been used to heat low-pressure-side condensate with steam of a high pressure chamber, thereby imparting a high temperature to the condensate to be supplied to the boiler. Concretely, the low-pressure-side condensate is caused to fall freely as droplets or liquid films in high pressure steam, and heated by convection heating. The use of the multistage pressure condenser can also widen the temperature difference between the temperature of cooling water and the temperature of saturated steam and decrease the area of the heat transfer surface.
With the conventional multistage pressure condenser, low-pressure-side condensate is caused to fall freely as droplets or liquid films in high pressure steam, and heated by convection heating. Thus, the time for which the droplets or liquid films are present in high pressure steam is lengthened to perform efficient heating. To lengthen the time for which the droplets or liquid films of the low-pressure-side condensate are present in high pressure steam, however, there is need to increase the height of falling, thus impeding compactness. If the falling height is minimized for achieving compactness, heating is insufficient, causing disadvantage to the efficiency of the plant.
The present invention has been accomplished in consideration of the above circumstances. It is the object of the invention to provide a multistage pressure condenser capable of achieving both of compactness and increased plant efficiency.
To attain the above object, the present invention, in a first aspect, provides a multistage pressure condenser having a plurality of chambers at different pressures and adapted to merge and pressure-feed condensates accumulated in the plurality of chambers, comprising:
a reheat chamber, partitioned off with a pressure barrier in a lower portion of a low pressure chamber, as the chamber on a low pressure side, for introducing and accumulating low-pressure-side condensate;
high pressure steam introduction means for introducing high pressure steam within a high pressure chamber, as the chamber on a high pressure side, into the reheat chamber; and
bypass means for merging high-pressure-side condensate bypassing the reheat chamber and the low-pressure-side condensate discharged from the reheat chamber to raise the temperature of the condensate.
According to the first aspect of the invention, the low-pressure-side condensate can be heated in the reheat chamber, and the high-pressure-side condensate can be merged with the low-pressure-side condensate without a drop in the temperature of the high-pressure-side condensate. As a result, the condensate in a high amount of heat exchange can be transported toward a condensate pump. Hence, a multistage pressure condenser achieving compactness and increased efficiency of a power plant can be constructed.
In a second aspect, the present invention provides a multistage pressure condenser having a plurality of chambers at different pressures and adapted to merge and pressure-feed condensates accumulated in the plurality of chambers, comprising:
a reheat chamber, partitioned off with a pressure barrier in a lower portion of a low pressure chamber, as the chamber on a low pressure side, for introducing and accumulating low-pressure-side condensate;
high pressure steam introduction means for introducing high pressure steam within a high pressure chamber, as the chamber on a high pressure side, into the reheat chamber;
low pressure condensate introduction means for introducing low pressure condensate into the reheat chamber; and
circulating flow generation means for generating a circulating flow in the condensate in the reheat chamber to cause surface turbulent heat transfer,
whereby heat transfer to the condensate by high-pressure-side steam is promoted.
According to the second aspect of the invention, because of convection heating in high-pressure-side steam and surface turbulent heat transfer due to a circulating flow, the low-pressure-side condensate undergoes satisfactory heat transfer in the reheat chamber, and rises in temperature efficiently. Consequently, there is no need to lengthen the time for which droplets dwell in the high pressure steam, and heating takes place efficiently. That is, heating of the low-pressure-side condensate is performed sufficiently, with the space for falling being minimized for compactness. Hence, it becomes possible to construct a multistage pressure condenser permitting compactness and increased efficiency of a power plant.
In the multistage pressure condenser, the circulating flow generation means may be constituted such that a flow-through hole, through which the low-pressure-side condensate flows downward, is provided in the pressure barrier, and that the circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate flowing downward through the flow-through hole.
In the multistage pressure condenser, moreover, the circulating flow generation means may be constituted such that a drip hole, through which the low-pressure-side condensate drips, is provided in the pressure barrier; a receiving member is provided within the reheat chamber for accumulating the low-pressure-side condensate dripping through the drip hole and allowing the low-pressure-side condensate to overflow; and the circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate overflowing the receiving member.
Also, in the multistage pressure condenser, the circulating flow generation means may be constituted such that a flow-through slit, through which the low-pressure-side condensate flows downward, is provided in the pressure barrier; and the circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate which flows downward through the flow-through slit, with a reverse flow thereof being suppressed.
Also, in the multistage pressure condenser, the flow-through slit may have a length-to-width ratio of 5 or more.
Also, in the multistage pressure condenser, the circulating flow generation means may be agitation means for directly agitating the condensate accumulated in the reheat chamber to generate the circulating flow.
Also, in the multistage pressure condenser, the circulating flow generation means may be constituted such that a pipe extending toward the reheat chamber is provided in the pressure barrier; and the circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate flowing downward through the pipe.
Also, in the multistage pressure condenser, the condensate accumulated in the reheat chamber may be partitioned by a partition wall into a plurality of sites to promote the circulating flow.
Also, in the multistage pressure condenser, the circulating flow generation means may be constituted such that a flow-through portion, through which the low-pressure-side condensate passes, is provided in the pressure barrier; and a condensate reservoir is provided which has an opening portion at a higher position than the water surface of the condensate accumulated in the reheat chamber, in which the low-pressure-side condensate passing through the flow-through portion is accumulated in such a state as to cause a circulating flow, and which allows the low-pressure-side condensate overflowing the opening portion to generate the circulating flow in the condensate accumulated in the reheat chamber.
In a third aspect, the present invention provides a multistage pressure condenser having a plurality of chambers at different pressures and adapted to merge and pressure-feed condensates accumulated in the plurality of chambers, comprising
a reheat chamber, partitioned off with a pressure barrier in a lower portion of a low pressure chamber, as the chamber on a low pressure side, for introducing and accumulating low-pressure-side condensate;
high pressure steam introduction means for introducing high-pressure-side steam within a high pressure chamber, as the chamber on a high pressure side, into the reheat chamber:
a drip hole provided in the pressure barrier for allowing the low-pressure-side condensate to drip therethrough;
a receiving member provided within the reheat chamber for accumulating the low-pressure-side condensate dripping through the drip hole and allowing the low-pressure-side condensate to overflow, so that a circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate overflowing the receiving member; and
bypass means for merging high-pressure-side condensate bypassing the condensate of the reheat chamber and the condensate of the reheat chamber to raise the temperature of the condensate.
According to the third aspect of the invention, because of convection heating in high-pressure-side steam and surface turbulent heat transfer due to the circulating flow, the low-pressure-side condensate undergoes satisfactory heat transfer in the reheat chamber, and rises in temperature efficiently. Consequently, there is no need to lengthen the time for which droplets dwell in the high pressure steam, and heating takes place efficiently. That is, heating of the low-pressure-side condensate is performed sufficiently, with the space for falling being minimized for compactness. Moreover, the high-temperature-side condensate can be merged with the low-temperature-side condensate, without a drop in the temperature of the high-temperature-side condensate, and the condensate in a high amount of heat exchange can be transported toward a condensate pump. Hence, it becomes possible to construct a multistage pressure condenser permitting compactness and increased efficiency of a power plant.
In a fourth aspect, the present invention provides a multistage pressure condenser having a plurality of chambers at different pressures and adapted to merge and pressure-feed condensates accumulated in the plurality of chambers, comprising
a reheat chamber, partitioned off with a pressure barrier in a lower portion of a low pressure chamber, as the chamber on a low pressure side, for introducing and accumulating low-pressure-side condensate;
high pressure steam introduction means for introducing high-pressure-side steam within a high pressure chamber, as the chamber on a high pressure side, into the reheat chamber; and
a pipe provided in the pressure barrier and extending toward the reheat chamber,
whereby a circulating flow is generated in the condensate of the reheat chamber by the low-pressure-side condensate flowing through the pipe, with the water level of the low-pressure-side condensate of the low pressure chamber being lowered.
According to the fourth aspect of the invention, because of convection heating in high-pressure-side steam and surface turbulent heat transfer due to the circulating flow, the low-pressure-side condensate undergoes satisfactory heat transfer in the reheat chamber, and rises in temperature efficiently, with the water level of the low-pressure-side condensate of the low pressure chamber being lowered. Hence, it becomes possible to construct a multistage pressure condenser enabling the low pressure chamber to be compact and the efficiency of a power plant to be increased.
In a fifth aspect, the present invention provides a multistage pressure condenser having a plurality of chambers at different pressures and adapted to merge and pressure-feed condensates accumulated in the plurality of chambers, comprising:
means for introducing low-pressure-side condensate into a high pressure chamber, the chamber on a high pressure side, and heating the low-pressure-side condensate with high-pressure-side steam.
According to the fifth aspect of the invention, the low-pressure-side condensate undergoes satisfactory heat transfer in the high pressure chamber by convection heating in high-pressure-side steam, and rises in temperature efficiently. Hence, it becomes possible to construct a multistage pressure condenser enabling the low pressure chamber to be compact and the efficiency of a power plant to be increased.
In the multistage pressure condenser, moreover, the means for heating may let the low-pressure-side condensate fall into the chamber on the high pressure side to generate a circulating flow in the condensate accumulated in the chamber on the high pressure side, catch condensate, which has been produced in a tube nest on the high pressure side, by a receiving member installed below the tube nest, and mix the caught condensate with the condensate, which has been accumulated in the chamber on the high pressure side, outside of the condenser.